Subcutaneous lead fixation mechanisms

Abstract

A medical device that includes a lead having a lead body extending from a proximal end to a distal end, and a housing having a connector block for receiving the proximal end of the lead body. A fixation mechanism is positioned proximal to an electrode coil located at the distal end of the lead body, and a fixation member or a plurality of fixation members extend from the fixation mechanism from a fixation member proximal end to a fixation member distal end. The fixation members are advanceable from a first position corresponding to the fixation member distal end being positioned along the lead during subcutaneous placement of the lead, to a second position corresponding to the fixation member distal end being positioned away from the lead to fixedly engage the lead at a target site.

1. A medical device system to be subcutaneously placed at a target site posterior to a heart of a patient, comprising:
 an electrode; 
 a lead having a lead body extending from a proximal end to a distal end and defining a lead axis, the electrode being positioned along the lead; 
 a fixation mechanism positioned along the lead body proximal to the electrode; and 
 a plurality of fixation members extending from the fixation mechanism, each of the plurality of fixation members being pliant and forming a fixation member proximal end and a fixation member distal end, each of the plurality of fixation members having:
 a first position corresponding to the fixation member distal end being positioned generally against the lead body during subcutaneous placement of the electrode; 
 a second position corresponding to the fixation member distal end being positioned away from the lead at an acute angle to the lead axis toward the proximal end of the lead to fixedly engage the electrode at the target site, each of said plurality of fixation members being resiliently biased toward the second position; and 
 a third position corresponding to the fixation member distal end being positioned away from the lead at an acute angle to the lead axis toward the distal end of the lead. 
 
 
     
     
       2. The medical device system of  claim 1 , further comprising a plurality of channels formed along the lead to receive the plurality of fixation members in the first position. 
     
     
       3. The medical device system of  claim 1 , further comprising a sheath capable of being positioned over the plurality of fixation members to position each of said plurality of fixation members in the first position and being removable from the fixation mechanism to advance the plurality of fixation members to the second position. 
     
     
       4. The medical device system of  claim 1 , further comprising a sheath having a length and configured to receive the lead, wherein the sheath includes a cutout portion extending the length of the sheath for receiving the plurality of fixation members as the lead is advanced through the sheath. 
     
     
       5. The medical device system of  claim 4 , further comprising an introducer for receiving the sheath, wherein the sheath extends to a distal end and has a diameter less than a diameter of a proximal end of the electrode, the distal end of the sheath engaged against the proximal end of the electrode, when the lead is positioned within the sheath, to advance the lead within the introducer. 
     
     
       6. The medical device system of  claim 4 , wherein the fixation member distal end ends outward from the sheath via the cutout portion. 
     
     
       7. The medical device system of  claim 1 , further comprising a housing having a connector block for receiving the proximal end of the lead body. 
     
     
       8. A medical device system to be subcutaneously placed at a target site in a patient, comprising:
 a coil electrode; 
 a lead having a lead body extending from a proximal end to a distal end and defining a lead axis, the coil electrode being positioned along the lead; 
 a fixation mechanism positioned along the lead body proximal to the coil electrode, the fixation mechanism extending from a proximal end having a first diameter approximately equal to a diameter of the lead and a distal end having a second diameter greater than the first diameter; and 
 a plurality of fixation members extending from the fixation mechanism being pliant and forming a fixation member proximal end and a fixation member distal end, each of the plurality of fixation members having:
 a first position corresponding to the fixation member distal end being positioned generally against the first diameter of the lead during subcutaneous placement of the electrode, 
 a second position corresponding to the fixation member distal end being positioned away from the lead at an acute angle to the lead axis toward the proximal end of the lead to fixedly engage the coil electrode at the target site, each of said plurality of fixation members being resiliently biased toward the second position; and 
 a third position corresponding to the fixation member distal end being positioned away from the lead at an acute angle to the lead axis toward the distal end of the lead. 
 
 
     
     
       9. The medical device system of  claim 8 , further comprising a sheath having a length and configured to receive the lead, wherein the sheath includes a cutout portion extending the length of the sheath for receiving the plurality of fixation members as the lead is advanced through the sheath. 
     
     
       10. The medical device system of  claim 9 , further comprising an introducer for receiving the sheath, wherein the sheath extends to a distal end and has a diameter less than a diameter of a proximal end of the electrode, the distal end of the sheath engaged against the proximal end of the electrode, when the lead is positioned within the sheath, to advance the lead within the introducer. 
     
     
       11. The medical device system of  claim 10 , wherein the fixation member distal end ends outward from the sheath via the cutout portion. 
     
     
       12. The medical device system of  claim 11 , wherein the electrode is positioned at a distal end of the lead and the plurality of fixation members extend away from the electrode when the plurality of fixation members are in the first and the second position and extend toward the electrode when the plurality of fixation members are in a third position during extraction of the lead. 
     
     
       13. The medical device system of  claim 12 , further comprising a housing having a connector block for receiving the proximal end of the lead body. 
     
     
       14. The medical device system of  claim 9 , further comprising a sheath capable of being positioned over the plurality of fixation members to position each of said plurality of fixation members in the first position and being removable from the fixation mechanism to advance the plurality of fixation members to the second position. 
     
     
       15. A method of subcutaneously positioning a lead of a medical device system to a target site distinct from a heart of a patient, the lead having a lead axis and an electrode located along a distal end of the lead and a fixation mechanism positioned along the lead body proximal to the electrode, the fixation mechanism having a plurality of fixation members each being pliant and having a fixation member proximal end and a fixation member distal end, comprising:
 advancing a distal end of a first elongated member to the target site; 
 inserting the lead within the first elongated member, the inserting advancing the plurality of fixation members from a first position corresponding to the fixation member distal end being resiliently biased to be positioned away from the lead at an acute angle to the lead axis toward the proximal end of the lead, to a second position corresponding to the fixation member distal end being positioned generally against the lead during subcutaneous placement of the electrode; and 
 extending the electrode and the fixation mechanism outward from the distal end of the first elongated member proximate the target sit to advance the plurality of fixation members from second position to the first position to fixedly engage the electrode at the target site; then 
 retracting the lead from proximate the target site to advance the plurality of fixation members from the first position to a third position corresponding to the fixation member distal end being positioned away from the lead at an acute angle to the lead axis toward the distal end of the lead. 
 
     
     
       16. The method of  claim 15 , further comprising inserting the lead within a second elongated member having a length prior to the inserting the lead into the first elongated member, the second elongated member having a cutout portion extending the length of the second elongated member for receiving the plurality of fixation members as the lead is advanced through the second elongated member. 
     
     
       17. The method of  claim 16 , wherein the second elongated member extends to a distal end and has a diameter less than a diameter of a proximal end of the electrode, the distal end of the second elongated member engaged against the proximal end of the electrode, when the lead is positioned within the second elongated member, to advance the lead within the first elongated member. 
     
     
       18. The method of  claim 17 , wherein the plurality of fixation members extend away from the electrode when the plurality of fixation members are in the first and the second position and extend toward the electrode when the plurality of fixation members are in a third position. 
     
     
       19. A medical device system comprising:
 a lead having a lead body extending from a proximal end to a distal end and defining a lead axis; 
 an electrode positioned along the lead body; and 
 a fixation mechanism positioned along the lead body including at least one fixation member extending from the fixation mechanism, being pliant and configured to maintain the lead in a fixed position relative to a body after subcutaneous placement, wherein the at least one fixation member is resiliently biased in a first position to extend in a first direction toward the proximal end of the lead at an acute angle relative to the lead axis, and change to a second position during lead retraction to extend in a second direction toward the distal end of the lead and at an acute angle relative to the lead axis. 
 
     
     
       20. The medical device system of  claim 19 , further comprising where the at least one fixation member is made of a flexible material. 
     
     
       21. The medical device system of  claim 19 , further comprising where the electrode is a coil electrode extending between the fixation mechanism and the distal end. 
     
     
       22. The medical device system of  claim 19 , further comprising a device coupled to the proximal end of the lead body. 
     
     
       23. The medical device system of  claim 19 , further comprising a sheath capable of being positioned over the plurality of fixation members to position each of said plurality of fixation members in a third position corresponding to the fixation member distal end being positioned generally against the lead during subcutaneous placement of the electrode and being removable from the fixation mechanism to advance the plurality of fixation members to the first position.